Study an important contribution to the understanding of pre-eclampsia.

A new study has found that women who develop high blood pressure in pregnancy (pre-eclampsia), may have hearts that pump less blood with each beat and this may help explain when they may be at a higher risk of heart disease and stroke later in life.

The findings, from Imperial College London in the UK, also suggested that pregnant women whose babies develop fetal growth restriction (FGR) (where a baby’s growth slows or stops before birth), may have differences in their blood circulation.

Pre-eclampsia is a condition that only occurs during pregnancy. It is diagnosed by high blood pressure in the mother, usually after 24 weeks of pregnancy. The condition affects one in 20 pregnancies and although most cases of pre-eclampsia cause no serious problems, in severe cases the condition can endanger the lives of both mother and child. It’s estimated around 1000 babies die every year because of pre-eclampsia, with most of the deaths due to premature birth.

For the study, called CONCEIVE, researchers tracked women from before they were pregnant, through pregnancy, and then after birth. The aim was to identify whether women had any pre-existing conditions that may increase their risk of pre-eclampsia, and FGR. In total the health of 218 pregnant women (before and during pregnancy) was tracked. Of these 15 (almost 7 per cent) went on to develop pre-eclampsia or fetal growth restriction (FGR).

The researchers stressed that the women’s heart function and blood circulation were still in the normal range, despite these differences.

Dr Christoph Lees, lead author from the Department of Surgery and Cancer at Imperial College London, said: “Pre-eclampsia and fetal growth restriction can have serious consequences for mother and baby, yet we’re still largely in the dark about their root cause – and how to prevent them. These findings suggest pre-existing issues with the heart and circulation may play a role – and provide an important piece of the jigsaw puzzle.”

He added the work might also help explain why previous studies have found women who develop pre-eclampsia and FGR may be at higher risk of heart disease and stroke later in life.

Before becoming pregnant, all women had tests to assess heart function and blood circulation. All of the women were outwardly healthy, with a normal weight and blood pressure. If a woman in the study was diagnosed with pre-eclampsia or FGR during the research, the scientists analysed her test results from before she became pregnant, and in the early stages of her pregnancy. They then compared these with women who had a healthy pregnancy.

The results revealed that although the women’s heart and blood pressure were still in the healthy range, their hearts pumped 16 per-cent less blood per minute than women who had healthy pregnancies, and their blood vessels were 17 per cent more resistant to blood flow. This caused their blood pressure to be slightly higher, but still normal.

Larger studies are now needed to confirm these findings, added Dr Lees.

He said although pre-eclampsia and fetal growth restriction had previously been linked to abnormalities with the placenta, these results suggest cardiovascular differences may also play a role. “The placenta only develops a few weeks into pregnancy, but we found that heart and circulation differences existed well before the placenta developed.”

Future work will also help establish if screening pregnant women’s heart function would be feasible for identifying the risk of pre-eclampsia.

Commenting on the study Dr Angie Brown, Medical Director of the Irish Heart Foundation, said it showed that even in some apparently health women, abnormalities in the vascular system are present and associated with a risk of severe hypertension – pre-eclampsia in pregnancy.

“More research is needed to confirm and understand these findings but is an important contribution to the understanding of pre-eclampsia. Hypertension is the leading cause of preventable death and disability with a high prevalence in Ireland. High blood pressure – hypertension is sometimes called the silent killer as its often asymptomatic this is another study that shows that it’s important for everyone to get a regular blood pressure check even if they think they are healthy as the only way to know your blood pressure is high is to have it checked.”

This study was published recently in the journal Hypertension and was funded by Action Medical Research, the National Institute for Health Research Imperial Biomedical Research Centre, and the Imperial College Health Charity in the UK.